l8 FIRST LESSONS IN DAIRYING 



Casein. The casein is suspended in milk in an 

 extremely finely divided or colloidal condition. It 

 is associated with the insoluble calcium phosphate. 

 It is coagulated by rennet and dilute acids, but not 

 by ordinary heat. It forms the basis of a great 

 many kinds of cheese. In cheese making most of 

 the fat is locked in the casein curd formed by rennet 

 or acid. 



Albumen. The albumen is similar to the casein 

 in composition, and in character resembles the 

 white of an egg. It is not precipitated or curdled 

 by rennet or acids, but is precipitated by heat. It 

 contains some sulphur. In cheese making it re- 

 mains in the whey. Together with casein, it forms 

 the group spoken of as protein compounds or 

 albuminoids. Rich in nitrogen, it contributes to the 

 supply of vital tissue and lean meat in the body. 

 The percentage of protein compounds is less vari- 

 able than the fat. They increase with the fat and 

 in the period of lactation, as Van Slyke shows in 

 the following table: 



Month of 

 Lactation 



1 . 



2 . 



3 



4 



5 - 



6 . 



7 



8 . 



9 - 

 10 



